Vinyl resins have been used to coat or cover a wide variety of materials. Most materials such as acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) may be coated with a vinyl resin without the use of the adhesive materials simply by dipping or spraying the material being coated with the resin coating. However, vinyl resin coverings particularly on materials like ABS are likely to be nonpermanent, in that a good bond between the materials is not formed. Within a short time after coating, peeling and cracking, etc., of the polymeric surface results. Further, if the coating or covering is to be used on surfaces which are subject to frictional contact, e.g., rubbing, etc., the covering or coating slips.
Several attempts have been made to securely bond vinyl resin coverings to various materials. Systems involving preheating of the material being coated, baking of the covering, etc., have all been used with only limited success. Presently, vinyl resins which are utilized in coverings are available as dispersions or suspensions. The vinyl resin is usually in the form of a paste dispersion of elastomers in a plasticizer (plastisol) and paste dispersions of such elastomers in a plasticizer and a volatile liquid (organisols). These materials have been particularly difficult to permanently adhere to surfaces, e.g., polymeric surfaces. In the use of such systems, it has been necessary to apply the vinyl resin dispersions only after the surface to which they are being applied has been treated with a primer. Various primers, e.g., vinyl butyral wash primer, have been utilized to aid in bonding of the vinyl resin dispersion. Among several disadvantages of known primers for vinyl resin include: insufficient adherence to permit forming and stamping operations subsequent to coating; the requirement of critical preheating of surfaces and curing of primer and/or coatings; a decreased adherency with aging; and cracking and breaking of the polymeric substrate. It is theorized that the cracking of the polymeric substrate is caused to great extent by migration of the plasticizer from the cured resin dispersions through the primer into the substrate.
The prior art has attempted to alleviate these problems by use of primers comprising various mixtures of acrylic resins. One such mixture comprises acrylic and epoxy resins. Such mixtures have been useful particularly where the surface to which the vinyl dispersion is being bonded is metallic. However, such mixtures do not adequately bond vinyl resin dispersions to polymeric materials, e.g., ABS. Further, they do not eliminate cracking and breaking of polymeric substrate by plasticizer, if the vinyl resin comprises plasticizer.